1. Field of the Invention
The present invention relates to wheelchairs and more particularly to hand or manual propulsion accessories to enable a wheelchair occupant to more readily propel the wheelchair in forward or rearward directions.
2. Description of the Prior Art
Although several hand propulsion devices have been developed for conventional wheelchairs, most wheelchairs are still propelled by the occupant driving the circular handrail attached to the side of each wheel. The reason appears to be the complexity of operating most such prior art devices. Devices such as shown in U.S. Pat. No. 3,189,368 Petersen 1965; U.S. Pat. No. 3,869,146 Bulmer 1975 and U.S. Pat. No. 5,263,729 Watwood 1993 are all representative of devices that must engage the periphery of the respective wheel. It is evident that the wheels of a wheelchairs are subject to wear, thereby creating adjustment problems for most of these prior art devices, as well as the fact that the periphery of the wheels collect dirt as well as road salt causing further problems in the operation of these mechanisms.
U.S. Pat. No. 3,877,725 Barroza 1975 and U.S. Pat. No. 4,354,691 Saunders et al 1982, describe hand propulsion devices that at least in part engage the handrail attached to the respective wheels on the wheelchair. Saunders et al includes a complicated structure requiring a specially designed handrail with a series of openings provided therein to cooperate with a lever arm having a bracket with a lug that must engage the openings in the handrail when the lever is pressed outwardly and then drives the wheelchair when the lever is pushed forwardly. The Barroza device is somewhat simpler and includes upper and lower pads that jam against the handrail to push forward or rearward the wheelchair. A brake pad engages the periphery of the wheel.
Many older people develop physical handicaps at a late stage in their lives requiring that they adapt themselves to the confines of a wheelchair and learn how to propel and navigate the wheelchair. Although hand propulsion devices according to the prior art can increase the mechanical advantage and thereby reduce the force that such occupants must exert to propel a wheelchair equipped with such devices, the relatively complicated manipulations required to operate the prior art devices, deters from their use.
In practically all prior art hand propulsion devices, the installation of such devices requires alterations to the wheelchair. In many cases, such as Saunders et al, a special handrail is necessary. Few if any prior art devices can be easily retrofitted to existing wheelchairs.
It is an aim of the present invention to provide an improved hand propulsion apparatus that can be mounted to existing conventional wheelchairs without modifications to the wheelchair.
It is a further aim of the present invention to provide an improved hand propulsion apparatus for a wheelchair that is simpler to operate by the occupant than the devices suggested by the prior art.
It is a still further aim of the present invention to provide a manual propulsion kit that is simpler in construction and requires fewer parts than the known hand propulsion devices.
A construction in accordance with the present invention comprises a manual propulsion kit for a wheelchair wherein the wheelchair includes a frame with two large wheels on either side of the frame and journaled to axles on the frame, each of the large wheels mounting a circular handrail, the kit including a pair of manual propulsion assemblies wherein each assembly includes a lever arm adapted to be journaled to the axle for rotational movement within a predetermined angular sector determined by a substantially vertical position and a position forward of the frame, a crank handle having a crank web member pivoted for rotation, at the end of the lever arm adjacent the handrail when the lever arm is mounted to the axle, about an axis coincident with the lever arm such that the crank member defines an arc and moves between a forward position forward of the lever arm, at a tangent to the handrail, and a reverse position extending rearward of the lever arm and at a tangent to the handrail, a crank handle grip mounted to the crank web member, friction means associated with the crank web member adapted to engage the handrail when pressure is applied to the crank handle grip, when the crank handle is in one of the forward and reverse positions whereby the manual propulsion assembly can be utilized to propel the wheelchair forwardly or rearwardly.
More specifically the friction means is in the form of at least a friction pad mounted to a backing plate that is fixedly mounted to the crank handle grip but underneath the crank web and the backing plate with the crank handle grip are journaled to the crank web so that the at least one friction pad can engage the handrail whether the crank handle is in the forward or reverse position.
In another embodiment of the present invention the friction means includes a bracket that is pivotally mounted to the lever arm adjacent and below the crank handle and the bracket includes a forward component extending forward of the lever arm and a rearward component extending rearwardly thereof and both components extend in a plane tangential to the handrail, and friction pads are mounted to the bracket components adapted to engage the handrail when pressure is applied to the crank handle in one of the forward and reverse positions.